Infants born to mother who use cocaine during pregnancy have greater morbidity and a higher rate of sudden death. The etiology of sudden death is unclear. Preliminary observations suggest the presence of multiple cardiovascular abnormalities such as greater left ventricular mass, persistent hypertension, greater prevalence of ST segment elevations and higher vagal tone. To study the cardiovascular effects on in-utero cocaine exposure the study has the following aims: to detect the cardiovascular abnormalities in the newborn period; to evaluate the relationship of cord blood plasma cholinesterase activity and the above abnormalities; and to study the natural history of these abnormalities during the first 2 months of life.